1. Field of the Invention
The present invention relates generally to crane systems and arrangements for marine vessel applications. More particularly, the invention relates to a travelling crane arrangement for a floating vessel.
2. Background of the Technology
Vessels utilized for anchor handling, such as so-called Anchor Handling Tug Vessels (AHTVs) are often equipped with a stern roller and a relatively heavy winch. When an anchor is to be deployed, an anchor rope, that may include a chain, a wire or a rope, is connected to the anchor, and the anchor is lowered into the sea over the stern roller by letting out rope from the winch. Retrieving an anchor is undertaken by performing the operations in reversed order. Large forces are encountered during such operations and sometimes assistance is needed from another vessel in order to ensure safe working conditions.
Conventional approaches for overcoming unsafe operations are described in, for example, WO2009/005367. The '367 publication proposes a roller that is parallel to the stern of the vessel and connected to two arms. The arms, which are hinged close to the stern of the vessel, are moving the roller between an idle position below the deck and an active position above the stern. When an anchor is to be deployed, the anchor is placed on the deck behind the roller. The roller is moved towards its active position, thus lifting the anchor at least partly off the deck. The anchor may be lowered clear of the stern as the rope is let out over the roller. A disadvantage of the equipment is that the roller is moving along a fixed path and does not offer the flexibility of a crane.
NO325335 shows a transverse crane that spans across a vessel. The crane includes a remotely operated arm for handling anchor equipment.